Pull-type tabs have been commonly used to enclose pouring openings in the lids of carbonated beverage cans, such as soft drink or beer cars. The pull tab construction includes a ring that is secured to the tab, and by initially pivoting the ring from a horizontal position to a vertical position, the seal will be broken to vent the pressure from the can. Continued upward pulling on the ring will tear the tab from the opening. Discarding of the tab has not only resulted in an environmental problem, but the sharp edge of the tab provides a hazard which can cause lacerations to the feet or clothing.
To avoid the disadvantages associated with the pull-tab, there has been recent activity in the use of push tabs in which the tab is integrally connected to the lid and is pushed inwardly into the can in order to open the pouring opening. In one form of push tab construction, a single hole or opening is formed in the lid of the can which is enclosed by the tab. In certain instances, the tab is fully cut or scored through the lid with the scored joint being sealed on the inside by a sealant. Alternately, the tab can be partially scored in which case no internal sealant is required. As the cans usually contain a carbonated soft drink or beer, there is substantial internal pressure acting against the underside of the tab, and thus it is difficult to depress the tab against the internal pressure exerted by the beverage.
To facilitate opening, certain lid constructions have utilized a pair of openings, one being a larger pouring opening and the second being a small vent hole, each closed by a tab. With this type of construction, the vent tab is initially depressed to vent the internal pressure. With the internal pressure vented, the larger pouring tab can then be easily depressed to open the pouring hole. This type of construction, however, has certain disadvantages in that the consumer must be educated as to the manner of opening the can, meaning that special instructions must be imprinted or embossed on the can lid, indicating the manner in which the can is to be opened.
In another type of push tab arrangement, both the upper and lower surfaces of the lid are scored to define the tab and the scored lines are slightly off-set to provide a weakened joint. To open this type of push tab construction, the consumer must initially push downwardly along one side edge of the tab to rupture the weakened joint in that area and then push downwardly along the opposite side edge of the tab to rupture the weakened joint at that location. This construction has a disadvantage in that substantial pressure must be exerted to open the tab, and the consumer must be educated as to the proper manner of operation.
Non-pressurized containers have been formed in the past with push tabs having sharpened points, which when depressed, will rupture a lining material to expose the contents of the container. Container constructions of this type are illustrated in U.S. Pat. No. 2,082,760. In the construction of this patent the contents are contained within a sealed bag or envelope located within an outer metal container. The lid is provided with a pointed tab and when the tab is depressed, the pointed tip will rupture the envelope to expose the contents.